New e-skin feels heat, textures and more :

Hyunhyub Ko and his team reports rubbery plastic-and-carbon film mimics the structure of human skin (new electronic skin), that can feel the raspy texture of sandpaper, the beat of someone’s pulse and even heat. But there’s more. It also can detect sound.
It’s the first time anyone has demonstrated an e-skin that can sense so many different types of stimuli. It can relay signals directly to brain cells, based on tests with cells that had been isolated from a mouse. Those cells got the skin’s message, too. They became more or less active depending on how hard researchers pushed on the skin.
Such work offers a blueprint for scientists to actually “bridge electronics with biology.
One day, such an e-skin might cover prosthetic limbs and plug directly into people’s nerve cells, he says. This would let people know if they were touching something hot or rough or sharp — just as real skin does. The artificial skin also could form the basis for soft, wearable medical devices.
Over the last several years, scientists have invented an assortment of electronic-skin components. These range from different soft materials to new types of sensors. Some sensors can recognize more than one type of stimuli, but only under just the right conditions. E-skins are still “far from having the capabilities that human skin has,” he admits. But the newly reported advances do bring the prospect of such a technology closer.
By mimicking the ultrasensitive skin of human fingertips, Ko and his colleagues designed their e-skin to detect many types of signals. The researchers placed a soft ridged film over thin bumpy sheets made from plastic and Graphene. (Graphene is a single-atom-thick sheet of carbon with a host of unusual properties.) Those thin bumpy sheets are only about as thick of a few layers of the plastic cling-wrap used to seal up kitchen leftovers.
Touching this e-skin pressed together the electrodes on the bumpy sheets. This caused an electric current to flow through the device, which was hooked up to a machine to measure such signals. The amount of current depended on how much the bumps compressed. This provided a gauge of the pressure.
Heating the Korean team’s e-skin also generated a current, showing that it could sense temperature, too. A strip of the e-skin placed on a person’s wrist let the researchers simultaneously measure skin temperature and blood pressure.
And ridges on this simulated skin help it detect texture. When researchers skimmed its surface over glass or sandpaper, the ridges vibrated. The pattern of those vibrations differed depending on what had touched it. Sensors in the skin picked up on those differences.
Sound waves also made the e-skin vibrate. It could “hear” noise from a speaker playing a famous lecture by the late physicist, Richard Feynman. The e-skin converted his words into electrical signals, and then sent them to a machine. This let the researchers judge how well the e-skin sensed sounds. It worked even better than an iPhone’s microphone, Ko concluded.